[Jacob-list] Lambing stories:

[Dr. David R. Lincicome]

1500 hrs/Friday 9 March 2001

Fred,

I applaud you for this message on reporting genetic defects in Jacob sheep.  This
is a message that should be a cornerstone of conservation for any animal be it
rare or abundant.  At the moment I am involved similarly with Wheaten Terriers,
for the fancy is seeing the genetic results of  years of inbreeding for esthetic
purposes beginning with just  a small group of animals.

David

Jacobflock at aol.com wrote:

> Fred Horak here.  Katrina has seen something unusual, a lamb without an anus;
> the defect is called artesia ani. Artesia ani is a congenital defect causing
> a build up of feces, distension of the abdomen and death.  There was a case
> of artesia ani in a Jacob reported last year; the result of very close
> breeding.
>
> A couple years ago and each from time to time, the "Journal of the JSC" has
> carried lists of, reports and articles on various Jacob birth defects.  Birth
> defects happen.  Some might be preventable by examining breeding
> relationships but they are not preventable if no one is willing to suggest
> they occur nor report them and seek a cause when they do occur.
>
> Bonking and burying a defect does nothing for the Jacob breed or breeders.
> For ten years, or longer, there has been one birth defect reported and shared
> among Jacob breeders, condylar displasia.  In the past  few years, more
> defects are being reported and their probable causes are being identified.
>
> For example, last year we reported our experience with Twinkle Toes; a case
> of adactyly, no hooves.  This year two more Jacob breeders reported the
> problem.
>
> Another defect, not previously reported, was reported this year, a lamb that
> looks like it has four ears (two extra small "ears"); perhaps otognathia.
> Has anyone else seen this defect?
>
> Cases of severe ataxia from condylar dysplacia (skull/spine joint
> misalignment) have been reported.  A watch for a lysosomal storage disease
> called gangliodosis, a progressive "spinal cord" problem...it occurs in pure
> bred cats, dogs, sheep and in some "close" human groups...(generally
> observed, say, in the first six months) has been requested and about six
> cases of gangliodosis from across the country have been reported.  It is
> genetic.
>
> Parrot mouth (brachygnathia), dwarfism and even infertility have been
> reported.
>
> There are many defects; lethal and sub-lethal.  The sub-lethal move through
> the breed quietly, unobserved, unreported and then someone says, "I think I
> have seen a problem".   If it remains unobserved, or worse, observed and
> unreported, the various lines are at risk.  Defects are most often autosomal
> recessive genes...autosomal means they can be carried by rams and ewes...they
> are not sex linked.  Recessive means that they are not seen until two
> recessives "match" and show the defect...they can get carried from generation
> to generation.  Defects most often appear and get passed by close breeding,
> inbreeding (line breeding gone bad).  The lethal defect is either non-viable
> or aborted; they just get buried.
>
> It is my initial observation (I am not a vet but we support..make the house
> and car payments...for several vets) that crossing the 15% inbreeding
> coefficient seems to show some dwarfism, crossing the 20-25% threshhold sets
> up an observable significant visible defect either in the subject itself or
> in its offspring.  The Jacob gene puddle is the prime source for defects; not
> getting out of the puddle by using different and unrelated rams can make the
> puddle a genetic defect mess.
>
> OPINION: Conservation depends on conversation, sharing observations.  We owe
> thanks to the Jacob breeders that have reported defects and remain anonymous
> and those that are willing to share their observations.  They have addressed
> this difficult issue as part of conserving the breed.  I am optimistic, that
> after ten years, the genetic health...not just the spots and horns...of the
> Jacob breed is being considered.  Registries are often thought of as lists of
> pure bred animals that look right. More than that, they are books of breeders
> willing to share genetic information vital to conservation breeding. END OF
> OPINION.
>
> Fred Horak
> 1165 E. Lucas Road
> Lucas,  TX  75002
>
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